Answer: See explanation
Step-by-step explanation:
There are three main types of letter in English Language and these are:
1. Formal letter
2. Semi Formal letter
3. Informal letter
1. Formal letter: This is a letter that's written by using a structured format and a formal language. This is used in companies, workplaces, governments establishments etc.
2. Semi-formal letter: This is a letter used in addressing someone that one knows or have a business relationship with such as one's advisor, assistant, etc.
3. Informal letter: This is a letter that's used in writing to people that we know and are close with such as relatives, siblings or friends. A friendly tone is used in an informal letter.